This topic is not entirely new for a lot of you but I did spend enough time researching and compiling reference information (re: REM connectors) that was not quickly available and thought I would share back to this forum. Hope it might help others.

Background on Issue:
My 2004 XJ8 had trouble starting the other day. In fact, I think I have been having a failing fuel pump for some time but thought it was other issues. Finally it would not start but engine does crank.

I performed the following list of trouble shooting steps:

1) listen for fuel pump startup and relay click on key II position (no sound)
2) check fuses in various fuse boxes (all good)
3) attach fuel pressure gauge to fuel rail (no pressure on engine crank)
4) reset fuel inertial switch on driver side (held down to reset)
5) using Multimeter, I tested voltage and resistance at various points to determine the circuits were all good.
6) all 'fingers' are now pointing to the fuel pump or a sub component with the fuel pump that has failed. Next step is replacement which is planned in next week.

To complete Step 5, I installed the JTIS reference software and printed out all applicable wiring diagrams and also printed the suggested 'pin point' diagnostic steps for Fuel System troubleshooting.

What I discovered with all this paperwork in front of me was, the JTIS assumes that you are a trained JAG mechanic (no surprise to me) but it did take time to figure out the wiring connectors they reference. So, I compiled a list of every pinout grouped by connector and then by a process of physical examination, I was able to determine which connectors were which on the Rear Electronic Module (REM). Sorry if this info is already compiled on the forums, but I couldn't find it by searching.

Here is the connectors on REM (I now labelled mine).
At the top left corner is CR71, Top Right is CR73.
On the bottom row starting at the left is CR13, then CR12, CR11 and finally CR4.

As an example, the JAG pin point process for the DTC code you are investigating will instruct you to "disconnect CR73 from REM" - "disconnect FP04 at Fuel Pump" - "measure resistance between CR73, pin03 (R) and FP04, pin04 (R)" - if the result is X, fix this - if the result is Y move on to the next step.

So as you can see figuring out the connectors is the first step and there is no diagram to reference and no labels on the actual device.

Anyway, after I did all the tests, I do have 12V to the fuel pump, which means the relay, fuses and circuits are checking out, but the pump is not energizing on key turn nor engine cranking. According to the JTIS guides, I now need to replace the pump.

At this point, I have the back seat out of car and the fuel pump is accessible from the factory cutouts below the circular plastic cover. It would seem to be a fairly straight forward process to disconnect the electric connection and pipe, loosen the seal ring, remove the bad pump, install new pump and seal and reconnect. I will report back on this final step as I have just placed the order for the pump.

btw, as a side note on pumps, I hope I bought a reasonable after market pump, which is an Airtex E8577M from Amazon for $344. This Airtex is referenced on their site as an exact match for JAG Part# C2C24164. The local JAG dealer was asking $650, plus they wanted the old one or I would pay another $177 for core. I think I might be able to rebuild the old one and keep it or sell on eBay for something.

I will report back on the installation and hope I have solved this no start issue.

 

Don't know if this works with your car (fairly sure it does) but what I do for my S-Type is look at the pinpoint JTIS stuff in one window and the Electrical Guide in more windows - one for the circuit, one for the previous page (for the harnesses and connectors) and if I need it the earlier parts of the Elec Guide for the module connector pictures, major harnesses etc. I flip between the windows to see it all within instants.

 

thats a good idea. In my case, I only have a desktop PC in my office that is capable of running JTIS, so I have to resort to preparing all the necessary paper printouts and then head to garage. The information seems to be there once you dig and cross relate it. There may be more physical connector label diagrams out there but I didn't find them.

This weekend I will install that fuel pump.

Does anyone know if draining the fuel from the tank is absolutely required for the 2004 XJ8. It looks like I can access and replace the pump from the back seat openings, but maybe I am missing something. My tank is half full.

 

I don't think that draining the tank is necessary but ensure that your battery is

disconnected before you start.

 

Update:
My buddy and I replaced the fuel pump tonight and now I am getting fuel pressure on the rail BUT it still is not firing up. It seems to want to catch but then doesn't. We ran out of time tonight, but I have put the battery charger on tonight and will try tomorrow.

Because it won't start it doesn't have any codes besides the one it showed before P1338. My U-Scan device seemed to have trouble clearing the codes (not sure why). I will try another attempt at clearing codes tomorrow.

Is there any resetting of ECM after a fuel pump gets installed, as I have not read anything. Would air getting into the tank cause some type of vapor lock?

I was so positive that my only problem was this fuel pump but something else is not right or the computer is thinking so .... sigh.

Scratching my head tonight ....

 

Good news!!!!

This morning after the battery was charged back up to 100% it cranked over quickly and started, although it sounded rough!!

It started up with this loud tapping sound in the engine, but that sound disappeared after the engine warmed up. I then did a test drive to the gas station and added 11gal of new fuel, then drove another 10miles or so.

Using my crappy scanner (Acron U-Scan - which I returned to store), I did take some images of Live Data showing what values when the car first started. Then I took another set of snapshot images while I was driving.

If anyone has a minute to comment on the following images, I would be grateful for your insight. Basically I need to know what I should be looking for in terms of baseline values. Once I get a baseline, I can then use this for future diagnostics.

Thanks in advance.





.

 

If the battery was off or too low, the PCM loses its learned values (KAM - see my sig). It'll run a bit rough till it relearns. Carry out the drive cycle if you want to speed it up - but it's a PITA and not needed.

 

I am wondering if I am having a similar problem with my 04 XJ8. I went to leave work for lunch and it started but sounded way wrong. It was vibrating and then just stopped. This was all in about 3 seconds. When I tried to restart it, it just cranked and sounded like it was trying to start but only on one cylinder. I could not get it to start. After work I checked every fuse (all three fuse blocks) that pertained to fuel or ignition. I did not find any bad fuses and all looked good. No corrosion or anything. In fact the fuses looked like brand new. I tried to start it again and it reluctantly started. It seemed a little rough but it smoothed out. I tried to rev the engine up and it died after it hit 3,000 rpm. It started back up with a little bit of cranking time. I nursed it out onto the road and drove a few miles kind of gently. I listened for anything unusual sounding but didn't notice anything. As I headed for home I tried a few times revving it again and there did not seem to be any issue. My drive home is only 9 miles. When I had it home I revved it in the garage and it seemed to be all normal. I turned it off, waited a few seconds and turn the key to see if I could hear the fuel pump. Couldn't really hear anything but I don't remember ever hearing the fuel pump before. Tried to start it and it started right up like normal.

I really don't want to end up stranded again. I live in a small town area and I have one of the only Jags around. I absolutely love the car and I want to fix something before it is too late.

Has this happened to anyone else?

 

In an S-Type, battery would be #1 suspect. See what other XJers say...

 

On another website a purported Jaguar mechanic said there are two fuel pumps and they can be accessed under the rear seat. One pump transfers fuel to the other side of the "saddle" tank, and when it is bad and fuel level low the above fault will appear. So for time being I should be ok to drive just keep more than 1/8 tank.

Fault occurred with about 40 miles range remaining, and when comes on fuel needle drops to complete empty. Fault clears itself while driving down the road and fuel needle comes up slightly. When fault returns fuel needle returns to zero. Engine runs normally.

 

You could read the correct details in the workshop manual if you like - free download....

 

Wonder just how many pumps go bad from running the fuel level too low, especially in warm weather.
Causing them, any car, to over heat from low fuel levels, as that's how their cooled, when they are electrical.

 

If the battery voltage should dip below a certain threshold (perhaps a tad below 12.0 VDC) while the engine is still cranking, the car will never ever start. The Jaguar XJ8's are extremely finicky that way. Personally,, I would focus on the battery first.

 

Hi to all,
Also need to replace defective fuel pump in my 2004 xj8. Recommended Airtex E8577M fuel pump is priced on Amazon at close to $1200 !!! Do they make them now out of gold? lol. Is any other pump on the market at more reasonable price ? After all didn't pay much more for the car. Any help will be highly appreciated

 

The XJ is a semi-exotic car and maintenance costs are truly in line with that. Earlier postings have detailed troubleshooting tips, but if your vehicle is hard to start and has more than 100k miles fuel pump should be changed.

If stranded due to failing fuel pump you can use a can of starting fluid sprayed into the intake, that works for fuel injected cars too.

From what I understand XJ has two fuel pumps. I get a fuel system fault when 1/8 tank or less so I think my second one is failing, but don't have time to look into it further right now other important projects and I just keep tank more than 1/4 full.